The only societal benefit that ever comes from wedlock (or any romantic relationship) is the creation of a new generation.
That's a strong statement, and it gets the back up of people who don't fit in that category.
It's fine to be annoyed that the person who brought the suit will be getting back a few hundred thousand dollars in inheritance taxes. That doesn't mean that society will get no benefit unless a marriage results in mixing of genes.
HTH!
Cheers,
Scott.